Sir, I read with great interest the recent article Chronic non-communicable diseases (BDJ 2014; 216: 487) and the evidence for periodontitis and its relationship with systemic conditions.1Preliminary results suggest that periodontitis contributes to cognitive impairment and people with poor oral hygiene and periodontitis may be at a greater risk of developing Alzheimer's disease (AD).2 The data supporting this association are, however, still limited.3,4

In March 2014 US National Institutes of Health founded prospective research in Germany (NCT02109705) which may explain the role of periodontal disease and especially the role of periopathogen Porphyromonas gingivalis in the initiation and progression of Alzheimer`s disease by determination of correlations between selected AD indicators (beta-amyloid protein) and periodontal disease determinants (enzyme activity, inflammatory mediators).5

Laboratory research conducted post-mortem has demonstrated the presence of products from bacteria Porphyromonas gingivalis in brains from patients suffering from dementia6 while other research suggests that several types of spirochetes, including periodontal pathogens, may be involved in the pathogenesis of AD with a probable causal relationship.7

Plausible biological mechanisms linking periodontitis and AD may include three possible routes: a) direct effects of oral pathogens; b) inflammatory response to perio pathogens; and c) the influence on vascular integrity. Immune responses of the brain tissue exposed to certain periodontopathic bacteria and/or their endotoxins may hypothetically lead to nerve cell damage.8 It is important to determine whether degenerative processes in the brain are initiated by inflammatory reactions as a result of periodontitis.